Osso literally means "bone" in Portuguese. However, in this song, it's used as an informal expression, similar to saying something is "tough" or "a hard nut to crack" in English.
The lyric "É osso, ir do topo da terra pro fundo do poço" translates to "It's tough, going from the top of the world to the bottom of the pit." This idiomatic use makes the word interesting and shows a common, expressive way Brazilians use language.
Have you ever looked back at a relationship and thought, "Wait a minute... that wasn't really love"? That's the powerful idea at the heart of Giulia Be's song "(não) Era Amor." The lyrics are a direct message to an ex who didn't appreciate what they had. The singer points out that now, after breaking someone's heart, the ex is suffering the consequences—they're "at war alone" while the person they hurt is finally "at peace."
The song is a lesson in karma and emotional responsibility. Giulia Be tells this person not to bother with "cheap flowers" and empty words because it's far too late. Instead, she advises them to sit with their pain and think twice before hurting someone again. It's a classic story of someone who had "the world in their hand" but lost it all, learning the hard way that actions have consequences.